Valve assembly for a cementing operation

ABSTRACT

A valve assembly for use in a wellbore includes a tubular body; a valve disposed in the tubular body and configured to control fluid communication through the tubular body; and a compound for coupling the valve to the tubular body. The upper end of the compound is configured to receive a plug, and the upper end is spaced from an inner surface of the tubular body.

BACKGROUND OF THE INVENTION Field of the Invention

Embodiments disclosed herein generally relate to a valve assembly for acementing operation.

Description of the Related Art

In the drilling of oil and gas wells, a wellbore is formed using a drillbit that is urged downwardly at a lower end of a drill string. Afterdrilling a predetermined depth, the drill string and bit are removed andthe wellbore is lined with a string of casing. An annular area is thusformed between the string of casing and the wellbore. A cementingoperation is then conducted to fill the annular area with cement. Thecombination of cement and casing strengthens the wellbore andfacilitates the isolation of certain areas of the formation behind thecasing for the production of hydrocarbons.

It is common to employ more than one string of casing in a wellbore. Inthis respect, the well is drilled to a first designated depth, and afirst string of casing is set in the wellbore. The first string ofcasing is hung from the surface, and then cement is circulated into theannulus behind the casing. The well is then drilled to a seconddesignated depth, and a second string of casing or liner is run into thewell. The second string of casing or liner is also cemented. Thisprocess is typically repeated with additional casings or liners untilthe well has been drilled to total depth.

In a conventional cementing operation, a float collar is attached to thebottom of the casing (or liner) string as the casing string is run intothe wellbore. A float collar located at the bottom of the casing stringis sometimes referred to as a float shoe. The float shoe typically has aone-way valve located within the shoe. The casing is run into thewellbore to the desired depth, and the cementing operation is performed.The cementing operation commences with a first plug being dropped intothe casing. The first plug typically has a through bore with a rupturedisk therein. Cement is pumped into the casing behind the first plug.Following the cement, a second plug is dropped into the casing andtypically does not have a through bore. After the first plug lands onthe float shoe, the pressure of the cement behind the first plug willincrease. When sufficient pressure is built up, the ruptured disk willfail, thereby opening the through bore. The cement flows through thebore of the first plug and past the one-way valve in the float shoeuntil the second plug reaches the first plug. The one-way valve allowsthe cement to flow out of the float shoe and into the annulus betweenthe casing and the wellbore, while preventing the cement fromre-entering the casing string.

The float shoe typically includes a tubular body, and the upper end ofthe tubular body couples to the casing. The interior of the tubular bodyincludes a one-way valve, which is held in place by cured cement. Theone way valve controls fluid communication through an axial bore formedin the cement. The lower end of the float shoe has a rounded nose formedof the cured cement.

During the cementing operation, the plugs will impact the float collarwhen they land on the float collar, thereby placing a bump pressure onthe top side of the float collar. The bump pressure places stress in thecement that can weaken the float collar and may lead to its failure.

There is, therefore, a need for an improved float collar capable ofwithstanding the stress from the bump pressure.

SUMMARY OF THE INVENTION

Embodiments described herein relate to a valve assembly. A valveassembly for use in a wellbore includes a tubular body; a valve disposedin the tubular body and configured to control fluid communicationthrough the tubular body; and a compound for coupling the valve to thetubular body. The upper end of the compound is configured to receive aplug, and the upper end is spaced from an inner surface of the tubularbody.

In another embodiment, a downhole tool assembly includes a plug and avalve assembly. The plug may include a landing surface. The valveassembly may include a tubular body; a valve disposed in the tubularbody and configured to control fluid communication through the tubularbody; and a compound for coupling the valve to the tubular body; whereinan upper end of the compound is configured to receive the landingsurface of the plug and wherein a ratio of an outer diameter of theupper end to an outer diameter of the landing surface is from 0.8 to1.2.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1 is a cross-sectional view of an embodiment of a wellbore during acementing operation.

FIG. 2 illustrates an exemplary embodiment of a valve assembly.

FIG. 2A is an enlarged, partial view of FIG. 2.

FIG. 3 shows a plug landed on the valve assembly of FIG. 2 during acementing operation.

DETAILED DESCRIPTION

FIG. 1 shows a schematic cross-sectional view of a wellbore 200according to one embodiment described herein. The wellbore 200 has atubular 202 which is being run into and set in the wellbore 200. Betweenthe wellbore 200 and the tubular 202 is an annulus 203. The tubular 202,as shown, is a casing; however, it could be any wellbore tubular such asa liner, a drill string, a production tubing, a coiled tubing, etc. Thetubular 202 is run into the wellbore 200 to a desired location. Acementing operation is then performed to fix the tubular 202 in thewellbore 200. The tubular 202 is coupled at its lower end to a valveassembly 204. The valve assembly 204 has a sleeve 210, a valve 206, abore 208, and a compound 212. The valve assembly 204, as shown, is afloat shoe; however, it is contemplated that a float collar or any othercementing assembly may be used. The valve 206 is shown as a one-wayvalve; however, other valves may be used such as a flapper valve, a gatevalve, a check valve, and a pop-off valve. Although shown as having onevalve 206, any number of valves may be used, such as two or threevalves, in order to increase reliability of the valve assembly.

FIG. 2 shows a cross-sectional view of an exemplary embodiment of avalve assembly 300 suitable for use as the valve assembly 204 shown inFIG. 1. The valve assembly 300 includes a tubular body 310, valves 320,a compound 340 for holding the valves 320 in the tubular body 310, and abore 308 formed in the compound 340. The tubular body 310 is attached tothe casing 202 during run-in. In one embodiment, the compound 340 iscement; however, the compound could be a composite, an impregnatedcement, a polymer, or any suitable compound, preferably a castablecompound. A bore 345 is created in the compound 340 to allow fluid toflow through the valve assembly 300. The valves 320 are configured tocontrol fluid flow through the bore 345.

The tubular body 310 has a connector end 307, an internally profiledportion 318, and a lower end 309. The connector end 307 may be a box endof a threaded connection for coupling the valve assembly 300 to thecasing 202. However, it is contemplated that the connector end 307 maybe any suitable type of connection for use in a downhole setting, suchas a pin end, a welded connection, etc. In one example, the lower end309 forms the bottom end of the casing 202. The lower end of the tubularbody 310 may include a rounded nose formed of the cured cement. However,the lower end 309 may be configured for connection to additional lengthsof casing 202 or another downhole tool.

In one embodiment, the internally profiled portion 318 is formed in theinternal surface of the tubular body 310. The internally profiledportion 318 is an irregular internal surface that enhances attachment ofthe compound 340 to the tubular body 310. The internally profiledportion 318 may extend a portion or the entire length of the interfacebetween the compound 340 and the tubular body 310. In the example shownin FIG. 2, the internally profiled portion 318 includes angular wickers312 formed on the internal surface of the tubular body 310. As shown,each wicker 312 is a circumferential groove having a downward facingshoulder, a flat wall, and an upward facing shoulder. The flat wall isrecessed from the internal diameter of the tubular body 310. The angularwickers 312 provide an irregular surface which facilitates retaining thecured cement within the tubular body 310.

In another embodiment, the internally profiled portion 318 includes aplurality of radiused portions formed in the internal surface of thetubular body 310. The plurality of radiused portions has a series ofhills and valleys. The hill is any part of the internal profiled portion318 which culminates toward the interior of the tubular body 310. Thevalley is any part of the internal profiled portion 318 which culminatestoward the exterior of the tubular body 310. In one embodiment, the hillhas a radius that is larger than a radius of the valley. In one example,the ratio of the radius of the hill to the radius of the valley rangesfrom 1.5:1 to 3:1. The distance between two hills may be from 1 inch to5 inches. In another embodiment, radius of the hill and the valley maybe different from the adjacent hill and valley. In one example, thehills and valleys create an undulated surface with no abrupt changesfrom one radius to the next. In another embodiment, the internalprofiled portion forms a sinusoidal wave. In yet another embodiment, theinternal profiled portion forms a spiral pattern.

The valves 320 are held in the tubular body 310 by the compound 340.

Although two valves 320 are shown, it is contemplated the valve assembly300 may include a single valve or three or more valves 320. The valves320, as shown, are one-way valves having a body 323, a plunger 324, anda biasing member 326 for biasing the plunger 324 toward the closedposition. The biasing member 326 is shown as a coiled spring; however,it should be appreciated that the biasing member may be any membercapable of biasing the valve 320 toward the closed position, such as aresilient member, a leaf spring, a fluid bias, etc. The valves 320 areconfigured to selectively control fluid flow through the bore 345 of thevalve assembly 300. The valves 320 open when the pressure above thevalves 320 is sufficient to overcome the biasing force of the biasingmembers 326. The valves 320 close when the pressure is no longersufficient to overcome the biasing force. Because the valves 320 areone-way valves, when closed, the valves 320 prevent the cement or otherfluid from re-entering the casing 202

In addition to retaining the valves 320, the compound 340 forms a seat305 at the up-hole end of the valve assembly 300. The seat 305 isconfigured to receive the first plug 214 during the cementing operation.The upper surface of the seat 305 includes an optional landing plate 335for contacting the first plug 214. In one embodiment, the upper end ofthe compound 340 is spaced from the internal surface of the tubular body310 such that a gap 350 is formed between the upper end and the internalsurface, as shown in FIGS. 2 and 2A. In one example, the outer diameterof the upper end of the compound 340 is smaller than the inner diameterof the tubular body 310 such that the upper end does not contact theinner surface of the tubular body 310. For example, the outer diameterof the upper end ranges from 60% to 99% or from 75% to 97% of the innerdiameter of the tubular body 310. The gap 350 may be an annular gap. Inone embodiment, the upper end of the compound 340 extends into theconnector end 307. In this respect, the gap 350 may exist between theupper end and the threads on the internal surface of the connector end307. A tapered portion 352 of compound 340 angles outwardly from theupper end toward the tubular body 310. If a landing plate 335 ispresent, then the tapered portion 352 may begin from the outer diameterof the landing plate 335 and angle outwardly and downwardly toward thetubular body 310. In one embodiment, the angle between the tubular body310 and the tapered portion 352 of the compound 340 ranges from 1° to75°; from 5° to 60°; from 10° to 45°; or from 20° to 35°. Although thetapered portion 352 is shown as a straight line, the tapered portion 352may be curved, such as a concave or convex shape, or may be undulated.In another example, the tapered portion 352 may include one or moreangled bends. In one embodiment, the tapered portion 352 may intersectthe internally profiled portion 318 of the tubular body 310. Forexample, the tapered portion 352 may intersect a wicker 312 of theinternally profiled portion 318, as shown in FIGS. 2 and 2A. In thisexample, the tapered portion 352 intersects a downwardly facing shoulderof the wicker 312. In another example, the tapered portion 352 mayintersect a non-profiled portion of the tubular body 310.

In one embodiment, the gap 350 is sized such that the outer diameter ofthe upper end is comparable to the outer diameter of surface of thefirst plug 214 contacting the upper end. In one example, a ratio of theouter diameter of the upper end to the outer diameter of the contactsurface ranges from 0.8 to 1.2; from 0.85 to 1.15; or from 0.95 to 1.05.

In operation, the casing string 202 is equipped with a valve assembly300 and lowered into the wellbore 200. After reaching the desired depth,the cementing operation is commenced. The cementing operation begins bydropping a first plug 214 into the interior bore of the casing 202.Cement 216 is supplied behind the first plug 214. A second plug 218 isplaced behind the cement 216. A push fluid is pumped behind the secondplug 218 to push the plugs 214, 218 and the cement 216 downhole. Thepushing fluid may be any fluid capable of pushing the second plug 218through the casing 202, such as drilling mud, water, etc. The first plug214 travels down the casing 202 until it lands on the valve assembly300. FIG. 3 shows an exemplary first plug 214 landed on the landingplate 335 of the valve assembly 300. The first plug 214 includes alanding surface 275 for contacting the landing plate 335. In thisexample, the outer diameter of the landing surface 275 is slightlysmaller than the outer diameter of the landing plate 335. A gap 350exists between the outer diameter of the landing plate 335 and the innerdiameter of the tubular body 310. With the first plug 214 engaged withthe valve assembly 300, a bump pressure is created between the firstplug 214 and the valve assembly 300. In this example, because the outerdiameter of the plate or upper end is comparable to that of the plugsurface 275, the stress created by the bump pressure and exerted on thecompound 340 is reduced. The pushing fluid increases the pressure behindthe first plug 214 until the pressure is sufficient to burst the rupturedisk 276 of the first plug 214.

After the rupture disk bursts, the cement 216 flows through the firstplug 214 into the bore 345 of the valve assembly 300. The pressure ofthe cement 216 is sufficient to push the plungers 324 down, therebyopening the valves 320. The cement 216 is allowed to flow through thevalve assembly 300 and out into the annulus 203. The cement 216continues to flow out into the annulus 203 until the second plug 218lands on the first plug 214. When the second plug 218 lands on the firstplug 214, the valves 320 close fluid communication through the bore 345,thereby preventing the cement 216 from flowing back into the tubular202, which is also known as U-tubing.

The cement 216 is allowed to cure in the annulus 203. A milling ordrilling tool then lowers into the tubular 202 to mill out the secondplug 218, the first plug 214, and the valve assembly 300. If necessary,the wellbore 200 may be drilled further and any number of additionaltubulars 202 placed into the wellbore 200 in the same manner asdescribed above.

In one embodiment, a valve assembly for use in a wellbore having atubular body; a valve disposed in the tubular body and configured tocontrol fluid communication through the tubular body; and a compound forcoupling the valve to the tubular body; wherein an upper end of thecompound is configured to receive a plug and wherein the upper end isspaced from an inner surface of the tubular body.

In another embodiment, a downhole tool assembly includes a plug and avalve assembly. The plug may include a landing surface. The valveassembly may include a tubular body; a valve disposed in the tubularbody and configured to control fluid communication through the tubularbody; and a compound for coupling the valve to the tubular body; whereinan upper end of the compound is configured to receive the landingsurface of the plug and wherein a ratio of an outer diameter of theupper end to an outer diameter of the landing surface is from 0.8 to1.2.

In one or more of the embodiments described herein, the compoundincludes a tapered outer portion extending outwardly from the upper endtoward the inner surface the tubular body.

In one or more of the embodiments described herein, an angle between theinner surface and the tapered outer portion is from 5° to 60°.

In one or more of the embodiments described herein, the valve assemblyincludes a landing plate disposed on the upper end.

In one or more of the embodiments described herein, the tubular bodyincludes an internally profiled portion.

In one or more of the embodiments described herein, the internallyprofiled portion includes a first radiused portion culminating in afirst minimum radius toward an exterior of the tubular body; and asecond radiused portion culminating in a second minimum radius toward aninterior of the tubular body.

In one or more of the embodiments described herein, the internallyprofiled portion includes a plurality of angled wickers.

In one or more of the embodiments described herein, the internallyprofiled portion is undulated.

In one or more of the embodiments described herein, the first minimumradius is larger than the second minimum radius.

In one or more of the embodiments described herein, an outer surface ofthe compound tapers outwardly from the upper end toward the innersurface of the tubular body.

In one or more of the embodiments described herein, the compoundincludes a tapered outer portion extending outwardly from the upper endtoward the inner surface the tubular body.

In one or more of the embodiments described herein, the tapered outerportion intersects the internal profiled portion of the tubular body.

In one or more of the embodiments described herein, the valve is aone-way valve.

In one or more of the embodiments described herein, the upper endextends into a connection of the tubular body.

In one or more of the embodiments described herein, the valve assemblyincludes a landing plate disposed on the upper end for receiving thelanding surface.

In one or more of the embodiments described herein, the valve assemblyincludes two valves.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

1. A valve assembly for use in a wellbore, comprising: a tubular body; avalve disposed in the tubular body and configured to control fluidcommunication through the tubular body; and a compound for coupling thevalve to the tubular body; wherein an upper end of the compound isconfigured to receive a plug and wherein the upper end is spaced from aninner surface of the tubular body.
 2. The assembly of claim 1, whereinthe compound includes a tapered outer portion extending outwardly fromthe upper end toward the inner surface the tubular body.
 3. The assemblyof claim 2, wherein an angle between the inner surface and the taperedouter portion is from 5° to 60°.
 4. The assembly of claim 1, furthercomprising a landing plate disposed on the upper end.
 5. The assembly ofclaim 1, wherein the tubular body includes an internally profiledportion.
 6. The assembly of claim 5, wherein the internally profiledportion includes: a first radiused portion culminating in a firstminimum radius toward an exterior of the tubular body; and a secondradiused portion culminating in a second minimum radius toward aninterior of the tubular body.
 7. The assembly of claim 5, wherein theinternally profiled portion includes a plurality of angled wickers. 8.The apparatus of claim 5, wherein the internally profiled portion isundulated.
 9. The assembly of claim 5, wherein the first minimum radiusis larger than the second minimum radius.
 10. The assembly of claim 5,wherein an outer surface of the compound tapers outwardly from the upperend toward the inner surface of the tubular body.
 11. The assembly ofclaim 10, wherein the compound includes a tapered outer portionextending outwardly from the upper end toward the inner surface thetubular body.
 12. The assembly of claim 11, wherein the tapered outerportion intersects the internal profiled portion of the tubular body.13. The assembly of claim 1, wherein the valve is a one-way valve. 14.The assembly of claim 1, wherein the upper end extends into a connectionof the tubular body.
 15. A downhole tool assembly, comprising: a plughaving a landing surface; and a valve assembly, having: a tubular body;a valve disposed in the tubular body and configured to control fluidcommunication through the tubular body; and a compound for coupling thevalve to the tubular body; wherein an upper end of the compound isconfigured to receive the landing surface of the plug and wherein aratio of an outer diameter of the upper end to an outer diameter of thelanding surface is from 0.8 to 1.2.
 16. The assembly of claim 15,wherein the compound includes a tapered outer portion extendingoutwardly from the upper end toward an inner surface the tubular body.17. The assembly of claim 16, wherein an angle between the inner surfaceand the tapered outer portion is from 5° to 60°.
 18. The assembly ofclaim 17, further comprising a landing plate disposed on the upper endfor receiving the landing surface.
 19. The assembly of claim 15, whereintubular body includes an internally profiled portion.
 20. The assemblyof claim 15, wherein the valve assembly includes two valves.